The long term goal of this research is to commercialize a neurostimulation system to treat post- amputation pain. Approximately 1.8 million individuals in the U.S. are living with an amputation, and about 185,000 individuals undergo an amputation each year. Post-amputation pain has a high incidence (95%) and frequently causes further disability, depression, and reductions in quality of life. Existing long-term pain therapies are inadequate long-term and are expensive (totaling up to $2.7-13 Billion/yr in the U.S.). We successfully completed the previous Phase I project and demonstrated the feasibility of relieving post- amputation pain in 88% of subjects during in-clinic testing with a method of peripheral nerve stimulation (PNS) that selectively activates target fibers using a single electrode placed remote from the nerve. Also, we conducted a 2-wk home trial of temporary percutaneous stimulation, and all subjects that completed the trial experienced clinically significant pain relief (average=76%) while receiving 24hr/day stimulation, confirming that pain relief can be sustained as long as stimulation is delivered. Single remote electrodes avoid the invasiveness previously limiting PNS. Selective remote stimulation also enables the use of a flexible, self- anchoring lead, which will reduce complications common with existing methods that use inelastic, non- anchoring leads. As well, implantable pulse generators (IPG) designed to be placed in the limb would enable the lead to deliver stimulation to nerves in the limbs without crossing the hip or shoulder. Avoiding joints reduces the repeated flexing/bending that frequently because hardware failures with existing systems. The goal of the present Phase II project is to develop an IPG with the technical capability to deliver the selective remote stimulation validated to relieve pain in the previous Phase I study. The new IPG is needed because no existing IPG can deliver the required parameters for selective remote stimulation. Also, no existing IPG is sufficiently thin and contoured to be placed comfortably in the amputee's residual limb and able to deliver the unique combination of stimulation parameters necessary to provide highly effective pain relief. To achieve the Phase II goal, the battery, packaging, and charging subsystem will be designed to enable implantation in the limbs and safe recharging (Aim 1); the circuit board assembly will be designed to deliver the required stimulation parameters for selective remote stimulation (Aim 2); and the IPG be assembled and tested for safety and reliability (Aim 3). Each aim will be considered successful if all verification/validation tests for the respective aims are passed. The outcome of this work will be a rechargeable IPG that can deliver selective remote stimulation, which was demonstrated to be highly effective for post-amputation pain. After completion of this Phase II study, the IPG will be ready for use in future preclinical and clinical studies required to obtain FDA approval. The successful development of this IPG will complete the commercial stimulation system, which also consists of a trial system and coiled, self-anchoring implantable lead ideal for PNS in the limbs.